The present invention generally relates to automatic cut-sheet feeding apparatuses, and more particularly to an automatic cut-sheet feeding apparatus incorporated into an image forming apparatus such as a laser printer and the like.
In order to improve the reliability of the laser printer, the automatic cut-sheet feeding apparatus in this laser printer is required to positively feed out only the single uppermost cut-paper out of the stack of cut-sheets one by one irrespective of the kind of cut-sheet.
FIG. 1 shows the conventional automatic cut-sheet feeding apparatus 10.
A pad 11 is urged by a coil spring 12 so as to be pressed into contact with a peripheral surface of a feed roller 13 made of rubber at the bottom thereof, as shown in FIG. 2. A stack of cut-sheets 14 are placed on a cassette 15, and the uppermost cut-sheet 14-1 of the stack of cut-sheets 14 is pressed against the feed roller 13.
When the feed roller 13 is rotated in a direction A, the uppermost cut-sheet 14-1 is normally fed in a direction B and passes between the feed roller 13 and the pad 11.
In the case where the cut-sheets are a special kind so that an attraction force between two cut-sheets due to static electricity is relatively large, a cut-sheet 14-2 just below the cut-sheet 14-1 is fed together with the uppermost cut-paper 14-1 by the feed roller 13 as indicated in FIG. 3.
A portion 16 on the pad 11 just preceding a contact point 17 where the pad 11 comes into contact with the feed roller 13 functions to stop the leading end 14-2a of the cut-sheet 14-2, and thereby to restrict further feeding of the cut-sheet 14-2.
However, the feed stopping function of the portion 16 is not sufficient, and the cut-sheet 14-2 slips on the pad 11, and thus there may occur feeding such that two cut-sheets 14-1 and 14-2 are fed together one on top of the other, as shown in FIG. 4.
In order to prevent the occurrence of the aforementioned stacked-feeding as much as possible, the stack of cut-sheets 14 must be positioned so as to incline as much as 30.degree. with respect to the plane of the upper surface of the pad 11.
However, this arrangement is apt to make feeding of the cut-sheet 14-1 abnormal, and thereby causing jamming of the cut-sheets to occur.